The COVID-19 Pandemic and Associated Inequities in Acute Myocardial Infarction Treatment and Outcomes

This cross-sectional study investigates the association of the COVID-19 pandemic with treatment and outcome disparities among patients with acute myocardial infarction.


Introduction
The COVID-19 pandemic has placed unprecedented stress on the US health care system. 1,2 In addition to nearly 100 million confirmed cases of COVID-19 and more than 1 million deaths in the US, 3 COVID-19 created disruptions and delays to usual care, particularly for urgent and emergent conditions. Prior studies 4-7 suggested significant excess mortality from causes other than COVID-19 during the pandemic, including cardiovascular disease. Furthermore, direct and indirect outcomes associated with COVID-19 have been more pronounced among people from racially and ethnically minoritized groups. Black and Hispanic individuals experienced a 60% higher cumulative death rate from COVID-19 than White individuals, 8 and individuals from minority groups accounted for 70% of excess deaths indirectly associated with COVID-19. 9,10 Understanding the association of COVID-19 with health care outcomes is essential to efforts to limit the number of excess non-COVID-19 deaths, especially for members of historically marginalized groups who have been the most affected by COVID-19. It is possible that excess deaths during the pandemic were predominantly due to delays in care, with patients seeking or receiving care later in their disease course due to care availability or concerns about contracting COVID-19. 7,[11][12][13][14][15] It is also possible that patients presenting with acute illnesses did not receive usual treatments due to staff or bed shortages. 16,17 The COVID-19 pandemic presents an opportunity to investigate whether health care systems under stress, as indicated by a high proportion of inpatients with COVID-19, provided lower-quality cardiovascular care and whether this decrease in quality of care was disproportionately large among members of racial and ethnic minority groups.
Prior investigators have shown that mortality rates after emergency surgery were higher in hospitals with a high number of COVID-19 cases, 18 although these findings were similar across racial and ethnic groups. 18,19 Others have previously reported that acute myocardial infarction (AMI) mortality increased during the COVID-19 pandemic. 15 It is not known if the COVID-19 pandemic has been associated with a disproportionate increase in mortality for cardiovascular hospitalizations among racial and ethnic minority groups. Therefore, using national Medicare data, this study aimed to answer 2 questions: Did patients hospitalized for AMI have different rates of revascularization, mortality, readmissions, or nonhome discharges in hospitals during weeks with a high COVID-19 burden compared with weeks with a low COVID-19 burden? If so, were these changes more deleterious among Black and Hispanic individuals than White individuals? The findings of this study may inform efforts by health care professionals and policymakers to create a more equitable health care system and improve the care of all patients with cardiovascular disease during the current pandemic and future pandemics. included beneficiary demographic information (age, sex, and self-reported race and ethnicity [Asian, Black, Hispanic, North American Native, White, and other], which is captured at the time of Social Security enrollment); International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) diagnosis and procedure codes; source of admission and date of admission; admission status; urgency of admission; discharge destination, date of death; and hospital identifier.
These patient-level data were merged with data from Centers for Medicare and Medicaid Services (CMS) Impact Files, which included information on hospital characteristics (geographic region, rurality, number of beds, mean daily census, disproportionate share hospital percentage, and resident-to-bed ratio).

Study Population
We identified 1 512 924 Hispanic, non-Hispanic Black (hereafter, Black), and non-Hispanic White

Statistical Analysis
Our first aim was to investigate whether patients admitted with AMI had different rates of revascularization (percutaneous coronary intervention or coronary artery bypass grafting during the index admission), 30-day mortality, 30-day all-cause readmission, or nonhome discharges (death or discharge to a skilled nursing facility or nursing home, inpatient rehabilitation facility, long-term care hospital, or hospital transfer) in hospitals during times with high weekly COVID-19 burdens compared with hospitals during times with low weekly COVID-19 burdens. Consider the exemplar outcome revascularization during the index admission for STEMI admissions: We specified an interrupted time-series model in which the underlying time trend for the outcome of interest is interrupted by an exogenous shock (ie, the start of the pandemic) at a particular time. The underlying time trend represents the hypothetical scenario in which the pandemic had not occurred (ie, the counterfactual). Typically, the intervention does not vary with time, and the intervention-associated outcome can be estimated as an intercept shift from the underlying time trend. In our case, however, the intensity of the COVID-19 shock (ie, the hospital weekly COVID-19 burden) varied in intensity and over time. 21 The model specifications are shown as follows for the baseline model (model 1): We treated results of unconditional analyses in which we did not adjust for any patient factors (other than age) and hospital characteristics as the main findings when we examined underlying disparities in outcomes and use of revascularization. We did this because Black and Hispanic individuals may be admitted with AMI (1) with more advanced disease and greater comorbidity burden because of the impact of social determinants of health and structural racism 22 and (2) to lower-volume and minority-serving hospitals. Hence, adjusting for disease severity, comorbidity burden, and hospital characteristics may have led us to underestimate the magnitude of the underlying disparities by adjusting away the effects of racism before hospital admission.
We also conducted post hoc analyses that were not planned as part of our original study design and were performed to address specific questions raised during the editorial review process. In these additional analyses, we examined changes in the number and severity (STEMI vs NSTEMI) of AMI admissions before and during the pandemic and changes in mortality outcomes over time during the early pandemic. We used negative binomial regression to estimate the weekly volume of AMI admissions as a function of period (pre-COVID-19 pandemic [January 2016 to February 2020] vs COVID-19 pandemic [March 2020 to November 2020] periods) and the type of AMI (NSTEMI vs STEMI). We expanded mortality models to include an interaction term between the weekly hospital COVID-19 burden (specified as a linear term) and the period during the pandemic (March to July 2020 vs August to November 2020) to investigate whether the earlier period was associated with a greater increase in mortality (at higher weekly hospital COVID-19 burdens) compared with the later period.
All statistical analyses were performed using Stata/MP statistical software version 17.0 (StataCorp). We used cluster robust variance estimators to account for the clustering of observations within hospitals. We estimated adjusted rates and outcomes using average marginal effects. The threshold for statistical significance was a 2-sided P < .05. A priori, we decided not to adjust for multiple comparisons as a conservative strategy [23][24][25] to reduce the likelihood of falsely concluding that increases in the COVID-19 burden were not associated with increases in disparities (ie, increasing the chance of a type II error). We believe this approach is justified to reduce the risk of missing a significant finding. Data were analyzed from October 2022 to June 2023.

Association of Hospital COVID-19 Burden With Changes in Revascularization
After adjusting for patient risk, the odds of revascularization among patients with NSTEMI overall

Association of Hospital COVID-19 Burden With Changes in Clinical Outcomes for NSTEMI
Among patients with NSTEMI overall, mortality, readmissions, and nonhome discharges increased more during weeks with high hospital COVID-19 burdens compared with hospitals before the pandemic ( Figure 1; eTables 3-5 in Supplement 1). The adjusted odds of mortality increased by 10%

Association of Hospital COVID-19 Burden With Changes in Clinical Outcomes for STEMI
Among patients with STEMI, rates of readmissions and nonhome discharges were not significantly higher in hospitals during weeks with a high hospital COVID-19 burden (eFigure 2 and eTables 3-5 in Supplement 1). Odds of mortality did not increase significantly in patients hospitalized during weeks with a hospital COVID-19 burden greater than 30% (aOR, 1.28; 95% CI, 1.00-1.64; P = .05) (eFigure 2 and eTable 3 in Supplement 1).  Figure 2B; eTables 3-5 in Supplement 1). However, Black and Hispanic individuals hospitalized with STEMI did not experience greater increases in mortality, readmissions, or nonhome discharges in hospitals during weeks with high hospital COVID-19 burdens compared with White individuals ( Figure 3B; eTables 7-9 in Supplement 1).

Results of Post Hoc Analyses
Compared with the prepandemic period, the weekly AMI admission rate decreased 5.2% during the pandemic (incident rate ratio [IRR], 0.95; 95% CI, 0.90-0.997; P = .04) (Figure 4). The overall IRR of STEMI to NSTEMI was 0.29 (95% CI, 0.28-0.29; P < .001), while the ratio of NSTEMI to STEMI decreased by 12.1% (IRR, 0.88; 95% CI, 0.83-0.93; P < .001) during the pandemic compared with before the pandemic. We did not find evidence that the 30-day mortality rate increased significantly  The patient model was adjusted for patient age, race and ethnicity, and risk, and the patient + hospital model was adjusted for patient age, race and ethnicity, and risk and hospital characteristics. The unadjusted model was adjusted for patient age and race and ethnicity. P values and adjusted rates are based on the patient model, which is plotted. OR indicates odds ratio.

Discussion
In this cross-sectional study of 1 319 924 hospitalizations for AMI, patients admitted with NSTEMI to hospitals during weeks with a high hospital COVID-19 burden were less likely to undergo revascularization and more likely to die within 30 days of admission and be discharged to a nonhome setting compared with patients admitted to hospitals during weeks with a low hospital COVID-19  The patient model was adjusted for patient age, race and ethnicity, and risk, and the patient + hospital model was adjusted for patient age, race and ethnicity, and risk and hospital characteristics. The unadjusted model was adjusted for patient age and race and ethnicity. P values and unadjusted rates are based on the unadjusted model, which is plotted. OR indicates odds ratio.
burden. The early phase of the pandemic was associated with a 5.2% reduction in weekly AMI admissions, with greater reductions in NSTEMI admissions compared with STEMI admissions. There was no substantial evidence of differential COVID-19 spillover among Black or Hispanic individuals hospitalized with NSTEMI or STEMI in mortality, revascularization, readmissions, or nonhome discharges.
The finding that a high hospital COVID-19 burden was associated with worse outcomes in patients with AMI is consistent with previous research showing that the pandemic was associated with a higher risk of mortality in adult patients undergoing major surgery in the US 18 and that AMI mortality increased during COVID-19 in a 12-hospital system. 15 The reduction in the revascularization rate for NSTEMI during the pandemic is also consistent with the decrease in urgent and emergent surgeries reported previously. 19 The lack of decrease in revascularization for STEMI may reflect the  .04 The patient model was adjusted for patient age, race and ethnicity, and risk, and the patient + hospital model was adjusted for patient age, race, ethnicity, and risk and hospital characteristics. The unadjusted model was adjusted for patient age and race and ethnicity. P values and adjusted rates are based on the patient model, which is plotted. less discretionary nature of percutaneous coronary intervention in this clinical setting. Long-term clinical consequences, particularly for the development of heart failure and other sequelae of AMI, should be monitored closely at the population level in coming years. The lack of an increase in disparities in revascularization rates for AMI during the pandemic is consistent with previous research 19 showing that Black and White individuals had similar reductions in elective cardiac surgery during the early phase of the pandemic.
Importantly, although the disparity in revascularization rates did not worsen during the pandemic in hospitals with high COVID-19 burdens, the existing gap in revascularization rates was nonetheless striking. Black and Hispanic individuals hospitalized after AMI had 35% to 45% lower odds of undergoing revascularization after AMI compared with White individuals. Given the proven, substantial clinical benefit of this treatment, the persistence of disparities in revascularization remains a significant cause of concern 3 decades after these disparities were first described. 26,27 It is unlikely that patient preferences alone can explain these disparities given that similar disparities have been observed in the allocation of heart transplants and ventricular assist devices after accounting for patient preferences. 28 These inequities likely reflect a combination of structural racism, which can impact access to high-quality care based on systematic historical divestment in predominantly Black communities, and individual or interpersonal racism, which can influence a clinician's likelihood of referring patients for appropriate procedures. 29,30 Limitations Our study has several potential limitations. First, in reporting our results on baseline disparities, we chose to present the results of our unadjusted analyses as the primary findings because Black individuals may present with more cardiovascular comorbidities compared with White individuals. 31 As a result, adjusting for differences in baseline health may reduce the magnitude of the disparities between Black and White individuals. Second, our analysis is based on Medicare patients aged 65 years and older, and results may not be applicable to younger populations. In particular, many patients younger than age 65 years, especially if they are Black or Hispanic, lack health insurance or have inadequate coverage. 32 In addition, our study may not include all Medicare Advantage patients, who are more likely to be Black or Hispanic. 33 Medicare Advantage plans may attract more individuals with low incomes owing to the availability of plans with no premiums, 33 and these patients may have been disproportionately affected by the pandemic compared with those in traditional Medicare. Third, our measure of hospital COVID-19 burden was based on Medicare patients and did not include all adult patients. Fourth, our analyses were conditional on hospital admission and did not account for disparities in AMI prevalence or death before hospital admission. Fifth, because this is a nonrandomized study and unmeasured confounding is likely, our findings cannot be used to make causal inferences.

Conclusions
In this cross-sectional study of more than 1.3 million AMIs, patients hospitalized in hospitals during weeks with large numbers of patients with COVID-19 had a lower likelihood of undergoing revascularization and a higher likelihood of death within 30 days, readmission, and discharge to a nonhome setting. Race and ethnicity-associated inequities did not increase significantly during the pandemic. These findings suggest that policy and clinical interventions are needed to ensure that hospitals can continue to provide high-quality, evidence-based care for all patients, even in times of strain or stress.